During drag&drop in PB, memory footprint can increase by up to 10 times. To achieve that you have to hover element over other for a couple of seconds.

Steps to reproduce:
1. Create a new Landing Page,
2. Choose some Layout; I've chosen the one that is on the attached image; layout comes from Demo
3. Add some blocks to one of the zones,
4. Try change the place of one of the blocks using drag&drop. But don't drop block at once, try to hover it over other blocks up and down.

During last step, memory footprint increases and also, placeholder is not changing positions smoothly.